Unconstrained definition of swap breaks types that pull in other namespaces with swap

[miscco]

Using an unconstrained swap function is problematic when interfacing with types that pull in multiple swaps from associated namespaces

consider this godbolt

This is breaking because both swap functions pulled in are ambigous.

One simple way to break this ambiguity is by adding a tie breaking in the form of std::type_identity_t. See this godbolt

[bernhardmgruber]

To elaborate, the problem is here: https://github.com/NVIDIA/cutlass/blob/main/include/cutlass/fast_math.h#L58

If an unqualified call to swap has arguments from both namespace std and cutlass, the compiler will see both std::swap and cutlass::swap, which is ambiguous.

[bernhardmgruber]

One solution, if you consume libcu++, is to just replace your swap with:

namespace cutlass {
  using ::cuda::std::swap;
}

[github-actions]

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